Meeting Abstract
The neural crest is a transient embryonic tissue giving rise to diverse cell types including melanocytes, peripheral and enteric cells, neurons and glia, smooth muscle cells, cartilage, and bone. Several genes are associated with neural crest migration, specification and differentiation. Here, we examined two morphotypes of Astyanax mexicanus: blind morphs living in caves throughout NE Mexico, and surface morphs drawn from rivers and streams in the same region. Cave morphs demonstrate important phenotypic alterations, including pigment regression, eye loss, and craniofacial asymmetry. We sought to understand if differences in neural crest gene expression and laterality may impact craniofacial differences. Towards this end, we evaluated key marker genes over early development, associated with migration (ets1, fgfr1), specification (fgf8, msx, and twist2a), and differentiation (sox10, tfap2a, snai2, and pax7) of the neural crest. Using whole-mount in situ hybridization, we assayed stage-matched individuals at 24, 36 and 72 hours post-fertilization. We discovered substantial expression differences both across development, and the right and left sides of the developing head of cavefish. These early alterations to neural crest gene expression may be associated with asymmetric alterations and bony fragmentation in adult cavefish. We believe these changes may prefigure cranial and directional asymmetries that arise later in the life history of the blind Mexican cavefish, which may explain lateral preferences in swimming patterns.
